In recent years, flat panel displays have been used in various products or various fields. Such flat panel displays have been required to have a larger size and a higher quality and to reduce power consumption.
In these circumstances, organic EL display devices including organic EL elements that utilize electroluminescence of organic materials have been attracting great attention as all-solid flat panel displays excellent in terms of, for example, being driven at low voltages and having fast response time and self-luminousness.
An organic EL element includes a pair of electrodes functioning as an anode and a cathode and an electroluminescence layer (hereinafter also referred to as an “EL layer”) disposed between the paired electrodes. An organic EL element is typically subject to moisture and oxygen. Intrusion of moisture and/or oxygen into an organic EL element promotes degradation of element properties of the organic EL element such as luminance. Various opinions have been offered about this degradation mechanism. One of them expresses that the degradation occurs due to oxidization or hydroxidization of a luminescent material and/or a cathode material. To inhibit degradation of organic EL elements, organic EL display devices are usually subjected to sealing. Specifically, for example, a sealant is provided around an organic EL element and a space enclosed with the sealant is filled with a resin desiccating agent.
Other examples of the technology for improving resistance of an organic EL element to moisture and oxygen include the followings.
Disclosed is a light emitting device in which a multilayer structure including an inorganic film, an organic film, and an inorganic film is not continuously provided from a lower portion of a sealant to a lower portion of a cathode of a light-emitting element (see, for example, PTL 1).
Also disclosed is an organic EL element that at least includes a first substrate, a sealing substrate opposing the first substrate while having a distance from the first substrate, a sealant that seals the first substrate and the sealing substrate and forms a sealed space between the first substrate and the sealing substrate, a source line and a gate line disposed on the first substrate, and a pixel electrode electrically connected to the gate line and the source line. The source line and the gate line are disposed in the sealed space. The organic EL element includes a source lead electrode that is connected with the source line and drawn from the sealed space. The source lead electrode is formed of the same film as the gate line (see, for example, PTL 2).
Also disclosed is a display device in which a layer containing a water-permeable organic material is sealed with a sealant (see, for example, PTL 3).
Also disclosed is a light emitting device that includes a substrate, a light-emitting element including an organic electroluminescence layer between a pair of electrodes stacked on the substrate in a thickness direction of the substrate, a lead wire disposed on the substrate and connected with the pair of electrodes of the light-emitting element, and a sealing member that seals the light-emitting element. An insulating layer containing an inorganic oxide is disposed on the substrate at at least a portion around the light-emitting element. The sealing member is bonded to the insulating layer containing the inorganic oxide and disposed around the light-emitting element using an adhesive interposed between the sealing member and the insulating layer (see, for example, PTL 4).
Also disclosed is an organic EL display device including a device substrate on which a pixel region is formed by arranging multiple pixels in a matrix, an organic EL element and a driving transistor for driving the organic EL element disposed in each pixel of the pixel region, and two inter-organic-layer insulating films disposed above the driving transistors and below the organic EL elements. A sealing substrate is bonded to the device substrate using a sealing member disposed over a region surrounding a pixel region. The two inter-organic-layer insulating films are divided by a dividing region disposed between the sealing member and the pixel region (see, for example, PTL 5).
Also disclosed is an organic electronics panel including an organic electronics element. In the organic electronics element, an organic compound layer, including a functional layer containing at least an organic compound, is tightly held between a pair of electrodes disposed on a support substrate. The organic electronics element is tightly sealed with a sealing member, covering the organic electronics element, between the sealing member and the support substrate in the state where the electrodes and the organic compound layer are tightly held. A junction of a lead portion of one of the electrodes and an electrode lead for connection with an external driving circuit is located within a tightly sealed region covered with the sealing member. The electrode lead is drawn from the tightly sealed region (see, for example, PTL 6).
Also disclosed is a display device including a support substrate, on which a display region is formed by arranging organic EL elements and a surrounding region is formed by disposing an organic-EL-element driving circuit around the display region. The organic EL element is sealed by an opposing substrate using a sealing resin. A wire is disposed in the surrounding region on the support substrate in which the driving circuit is disposed. An insulating film and a separation groove, which divides the insulating film, are also disposed on the support substrate. A protrusion is disposed on the opposing substrate at a portion opposing the separating groove. The protrusion is inserted into the separation groove (see, for example, PTL 7).
Also disclosed is a display device in which a sealant is disposed around an inter-layer insulator to prevent moisture or oxygen from intruding through an exposed portion of the inter-layer insulator (see, for example, PTL 8).